What is this thing on my hermit crab's shell? :eek1:

[small alien]

So, here's my majestic scarlet hermit crab

I noticed several weeks ago, there's someone or something living on the shell. It has a calcareous tube that is fixed along its length to the shell. It has a, forgive my ignorance, peduncle disk? Like the little shield a snail closes over the opening of its shell. Here it is.

After zooming in on this photo, I realized, is that yet another kind of small snail on the disc?!? :hmm3: Holy crap!

Appreciate hearing any thoughts on the life forms involved here. Hope that little sucker isn't a pyramidellid snail. Cheers.

 

[small alien]

Sorry the zoom in is so blury. Here's another shot. It has two little "antenna" that stick out when it's "open". I also thing I may have seen a strand trailing from it. Maybe? Hmmm.

 

[small alien]

And, yes, there also happens to be ANOTHER snail riding on the back of the hermit crab's shell when this was taken!!!

 

[small alien]

I can't help but marvel at that last shot. A hermit crab in a snail shell that has a snail on it with a snail on it and another snail on it.

 

[LeslieH]

It's a vermetid.

 

[small alien]

Thanks. Do you mean the tube creature attached to the shell or the tiny white snail on the tip of it?

Thanks.

 

[small alien]

And what does it do and what does it eat?

 

[ClownNut]

the tube looking creature is vermetid snail, but the white snail looks like pyramid snail.
i hope you dont have clam(s) or find more of the white snail anywhere else.

 

[small alien]

Hmmm. I wish I'd gotten that little sucker when I saw it. But I didn't see it until I blew up the picture and it'd been long gone by then. I don't have any clams and don't really plan on it. Hmmm. I know there are fish that will eat them. I'll keep an eye out for more and remove them.

I'm assuming the vermetid is harmless. Yes?

Thanks for taking the time. Cheers.

 

[LeslieH]

Vermetidae is a family of snails that have forgotten how to coil :- D Unlike other snails the shell forms a solid tube which is attached to hard surfaces. Most people think they are tubeworms when they first see the tube. Many snails have operculums - a hard structure on the bottom of the foot which is used like a door. When the snail is completely retracted into the shell the operculum seals off the opening. What you called the peduncle disk is an operculum. Vermetids feed by creating long strings or nets of mucus which catch bits of detritus floating in the water. After a while they suck the mucus back in to eat the detritus then start the whole process all over again. Talk about recycling! Harmless since they don't eat other organisms. On the other hand, some species of vermetids reproduce very rapidly in tanks & corals sometimes get irritated by the mucus nets. I believe the one on your hermit is one of the slow reproducing species that shouldn't be a problem.

The little white snail does look like a pyramid shell. Remember that they are specialized predators on other organisms so it could be on the vermetid because that's food for it. The other possibility is that it's just hitching a ride. In either case I would remove it.

 

[small alien]

Wow! Thanks. That's probably the best reply I've ever received on RC and that's saying something. Appreciate you taking the time. Best, Paul

 

[ROB2005]

Its even carrying a white feather duster, at the last picture, look straight up from the hermits visible eye on the pic halfway from the tip of the shell.

 

[small alien]

Oh, indeed!